Field of the Invention
The present invention relates to a numerical controller adapted to perform an operation based on table-format data, and more particularly to a numerical controller adapted to perform an operation based on table-format data by superimposing a plurality of tables of table-format data.
Description of the Related Art
There has been widely known an operation function on the basis of table-format data in a drive control method whereby to drive each control axis in synchronization with the motion of a reference axis. According to the method, the position information on each control axis in relation to the position of the reference axis is stored as table-format data provided in a memory or the like, and each control axis is operated in synchronization with the reference axis on the basis of the information stored as the table-format data.
In the operation function based on the table-format data, the table-format data that sets an axis position or auxiliary function such as an M code, corresponding to time, an axis position, an spindle position is stored beforehand in a memory or a storage device connected through a network, and the table-format data is read out in sequence to control each axis and the auxiliary function.
Japanese Patent Application Laid-Open No. 59-177604 and Japanese Patent Application Laid-Open No. 2003-303005 describe a path table operation function utilizing the operation function based on the foregoing table-format data, or a numerical controller referred to as electronic cam control. These technologies permit free tool operations not restricted by machining programs, making it possible to achieve reduced machining time and higher machining accuracy.
Further, an applied technology of the operation function based on the table-format data is described in Japanese Patent Application Laid-Open No. 2006-289583. According to the technology, in a cycle operation, such as a thread cutting operation, an operation of cutting in by a predetermined amount and a machining cycle operation, which has the same machining pattern, are separated, and two tables of table-format data, namely, the table-format data for directing the cutting in operation and the table-format data for directing the machining cycle operation, are stored. Further, the movement amount for the cutting in operation specified by the table-format data thereof and the movement amount for the machining cycle operation specified by the table-format data thereof are calculated and superimposed to drive each control axis. FIG. 12 illustrates an example in which the cycle table data for directing the machining cycle operation is read from the main table data for directing the cutting in operation to carry out a simultaneous operation.
According to the foregoing technology, in a cutting cycle that repeats the same machining cycle operation while carrying out the cutting in operation, two tables of table-format data are used to drive a single control axis, making it possible to superimpose the cutting in operation and the same machining cycle operation, as illustrated in FIG. 13.
However, the application of the technology described in Japanese Patent Application Laid-Open No. 2006-289583 is limited to the same machining cycle. The technology permits the simultaneous use of the table-format data for the cutting in operation and the table-format data for the machining cycle operation and allows the movement amounts in the individual operations to be superimposed. However, the technology allows only one table of table-format data to be used for one control axis in machining processes except for the machining cycle. FIG. 14 is a diagram illustrating the relationship between main table processing and cycle table processing. As illustrated, according to the prior art, it is required to call up a cycle table for a cycle operation from a main table for performing a cutting in operation, and the cycle table is used as a subordinate to the main table.
Hence, the axes and the spindle that are not involved in the cutting in operation and the machining cycle operation, an auxiliary function are controlled according to one table of table-format data. The axis movement paths, correction amounts and the like for the axes or the spindle are all described in one table of table-format data. In the case where a correction amount is required to be revised due to, for example, a difference in each machine or deterioration with age, there has been a problem in that a movement amount corresponding to the correction amount must be extracted from coordinate values described in one table of table-format data in order to make the revision.
Further, in the operation using the conventional table-format data, only one type of reference values can be specified in one table of table-format data, so that one reference value is selected from among a time reference, an axis position reference, and a spindle position reference to prepare the table-format data. Hence, in the case where a command involving two or more reference values is desired to be executed, e.g. in the case where an auxiliary function is desired to be output according to time, the position of an axis and the position of a spindle, there has been a problem in that, if the table-format data based on time is selected, then the position of the axis and the position of the spindle axis must be converted into the reference time to create the table-format data.